In addition to representing journeys in terms of distances, it is also known to describe such journeys in terms of the time that would be taken, possibly using various forms of transport. It is also known to produce maps with isochrones, showing locations that have a similar travel time, irrespective of geographical distance. However, these do not facilitate the ranking of candidate destinations in terms of their travel times. Existing technical solutions also present problems in terms of calculating travel times using available processing capabilities in real time.